In conventional immunoassays using antibodies, an antibody against a test substance is labeled with fine particle(s) of a fluorescent dye, an enzyme, a gold colloid or the like, and then the labeling substance is detected. Among them, when a plurality of test substances are to be simultaneously detected on a same support, there have been known methods in which the color tones of particles for labeling respective antibodies are varied so as to thereby carry out visual determination (JP Patent Publication (Kokai) No. 8-5635 A (1996) and JP Patent Publication (Kokai) No. 10-132817 A (1998)). However, although these methods are deemed to be excellent methods in terms of visual detection of test substances, they are disadvantageous when it comes to quantitative analysis of the test substances, because a plurality of detection systems have to be prepared corresponding to the light absorption wavelengths of the labels, which makes the detector complicated and expensive.
In addition, when analysis targets having different ranges of required measurement concentration are to be quantified with a same detector, general methods are such that a low-sensitive detection system is selected for a test substance at high concentration, as well as previously diluting a sample containing the test substance either by means of manual technique or an analyzer. Therefore, it has been difficult to quantify test substances having different ranges of required measurement concentration, on a same carrier.